A light-emitting diode element (hereinafter called light-emitting element briefly) has a compact size, provides favorable light-emitting efficiency and vivid color, of emission and has long operating life and excellent driving characteristics and the like. Accordingly, in recent years, it has been widely used as a light source for backlight of a color display device and for illumination purposes, for example. Thus, in embodiments, a light-emitting device including a light-emitting element will be described as the light-emitting device of the present invention.
A light-emitting device for emitting white light or a light-emitting device for emitting colored light has been proposed in recent years, and in this device, a light-emitting element mounted on a substrate is covered with a sealing member that may be a transparent resin, transparent glass, a phosphor resin or the like on. According to a known method, a light-emitting device of this structure is put into mass production by mounting a plurality of light-emitting elements collectively on a collective substrate (see Patent Literatures 1 and 2, for example).
FIG. 41 shows a conventional light-emitting device including a light-emitting element described in Patent Literature 1. This light-emitting device 100 includes: upper surface electrodes 102a in a pair formed on the upper surface of a resin substrate 102, the upper surface electrodes 102a including a first upper surface electrode 102a on which a light-emitting element 103 is directly mounted, and a second upper surface electrode 102a electrically connected to the light-emitting element 103 via a wire 104. The light-emitting device 100 further includes lower surface electrodes 102b for output formed on the lower surface of the resin substrate 102. The upper surface electrodes 102a in a pair and the lower surface electrodes 102b in a pair being external connection electrodes are electrically connected to each other via through hole electrodes 102c in a pair. The light-emitting element 103 is sealed with a transparent resin 105 on the substrate. A reflection member 106 intended to enhance light-emitting efficiency is provided on portions of the upper surface electrodes 102a in a pair except portions thereof required for bonding the light-emitting element with a wire.
FIG. 42 shows a conventional light-emitting device including a light-emitting element described in Patent Literature 2. This light-emitting device 200 includes upper surface electrodes 202a in a pair formed on the upper surface of a ceramic substrate 202 and electrically connected to a light-emitting element by directly mounting the light-emitting element on the ceramic substrate, and lower surface electrodes 202b in a pair for output formed on the lower surface of the ceramic substrate 202. The upper surface electrodes 202a in a pair and the lower surface electrodes 202b in a pair are electrically connected to each other via through hole electrodes 202c in a pair. The light-emitting element 203 is placed by flip-chip mounting on or above the upper surface electrodes 202a on the upper surface of the ceramic substrate 202 via bonding electrodes 203a or bumps in a pair formed on the lower surface of the light-emitting element 203. The light-emitting element 203 is sealed with low-melting point glass 205.
In the aforementioned light-emitting device 100 or 200 including a light-emitting element described in Patent Literature 1 or 2, a substrate with electrodes such as the resin substrate 102 or the ceramic substrate 202 is used to mount the light-emitting element on the substrate, and a resin to seal the light-emitting element is provided on the substrate to seal the light-emitting element. Accordingly, this substrate becomes an obstacle to reduce thickness of the light-emitting device 100 or 200 and a cause for deterioration of heat dissipation properties. Further, this substrate increases the number of components, and it also becomes a cause for increase in cost.
A light-emitting device which is prepared by eliminating a substrate in the end has been conventionally suggested to avoid the aforementioned problems (Patent Literature 3).
As shown in FIG. 43, this light-emitting device 300 includes electrodes 303a and 303c in a pair electrically connected to the light-emitting element 304, and an electrode 303b on which the light-emitting element 304 is to be mounted, with these electrodes being formed on the upper surface of a substrate 302 made of metal, plastic, silicone or the like. The light-emitting element 304 is fixed to the electrode 303b from above via an adhesive agent, and is connected via wires 305a and 305b to the element electrodes in a pair of the light-emitting element 304. Then, the light-emitting element 304 is sealed with a sealing member 306, and thereafter, the substrate 302 is removed by mechanical or chemical process. Thus, the electrodes 303a, 303b and 303c are finally exposed at one surface of the sealing member 306 to form electrodes of the light-emitting device 300.
The aforementioned conventional light-emitting device 300 is allowed to be reduced in thickness as a whole as the substrate 302 is removed at the end. Meanwhile, only the substrate 302 should be stripped while the plurality of electrodes 303a, 303b and 303c having been fixed tightly to the substrate 302 remain fixedly attached to the sealing member 306. This stripping is performed by mechanical or chemical process, making removal of the substrate 302 difficult work and lowering efficiency in this work. An additional problem also occurs in that it is hard to maintain the quality of the light-emitting device 300 at a constant level from which the substrate 302 has been stripped.